Abstract P2044: Silencing The LncRNA Vesper During Right Ventricle Pressure Overload Worsens Hypertrophic Remodeling And Function

Abstract

Pulmonary arterial hypertension (PAH) is a rare disease that includes familiar and idiopathic forms. Increased pressure in the pulmonary artery leads to pressure overload of the right ventricle (RV) and subsequent hypertrophic remodeling to maintain cardiac output (CO). While many therapies are available for the hypertrophic left ventricle (LV), the RV is known to involve distinct remodeling pathways and unfortunately, these are poorly understood, and no cure is available. To identify new regulatory mechanisms, total RNA sequencing was performed on hypertrophied mouse RV tissue. Focusing at differentially expressed long non-coding RNAs (lncRNAs), one specifically, Gm38399 , was observed to be consistently upregulated in the diseased RV compared to healthy controls. Compared to LV tissue, there was a similar expression at baseline, but interestingly, no increase in expression during LV hypertrophy. Therefore, we named this lncRNA right VE ntricular S pecific P ressure ov ER load ( Vesper ). To elucidate the mechanism, we determined the subcellular localization of Vesper , by subcellular fractioning followed by qPCR. Using Xist as nuclear, and Gapdh as cytoplasmic control, we found Vesper to be entirely nuclear. Furthermore, we were able to silence Vesper in vitro by using a specific GapmeR. Not only Vesper was silenced, but we also found two neighboring genes to be affected, namely Nav1 and Phlda3 . Interestingly, these genes were also differentially expressed in the diseased RVs. To determine the mechanism in vitro , chromatin isolation by RNA purification (ChIRP) was performed and the crosslinked RNA, DNA, proteins stored for further analysis. We also treated mice that underwent pulmonary artery banding (PAB) or sham surgery, with a weekly intraperitoneal injection of 10 mg/kg bodyweight GapmeR or a vehicle control. After 4 weeks, the mice underwent hemodynamic analysis before the RV tissue was isolated for histology and molecular analysis. Surprisingly, silencing of Vesper exacerbated pathologic RV remodeling, also in mice that received sham surgery. While further investigation is needed to understand the role of Vesper in PAH, our results so far suggest that expression of Vesper is necessary to maintain RV function during pressure overload.